People often think that one silver lining of climate change is that winter-related deaths will drop. But that’s not necessarily the case, researchers have found after studying mortality patterns in the UK. Over the past few decades, the link between cold days and winter deaths has largely vanished.

The team studied excess winter deaths, which are the additional number of deaths in winter compared to those in fall or spring. These deaths could be due to factors such as hypothermia, slipping on ice, or the flu.

From 1951 to 2011, the number of excess winter deaths in England and Wales became less variable, the researchers report in Nature Climate Change. In other words, mortality used to swing wildly from low to high from one year to the next; in recent years, it has been fairly stable.

The team then tried to figure out which factors could explain the yearly variation. From 1951 to 1976, the number of days when the temperature dipped below 5 degrees Celsius seemed to be partly responsible. Housing features, such as central heating and hot water, and the severity of the flu also played a role.

But from 1976 to 2011, only flu activity explained the variation, the researchers found. That means that “milder winters resulting from climate change are unlikely to offer a winter health dividend,” the team writes. Instead, winter deaths have been dropping because houses now provide better protection from the cold, health care has improved, and people at risk are getting more support.

In fact, climate change could even increase winter deaths by making the weather more variable. Sudden drops in temperature have become more common in the UK, and people could be “caught off-guard by abrupt changes,” the researchers warn. They recommend that policymakers continue to encourage housing upgrades, such as improved insulation, and to work toward higher flu vaccination rates. — Roberta Kwok | 25 February 2014